The Islamic State group on Monday claimed responsibility for an attack on a nightclub in the Turkish city of Istanbul that killed 39 people on New Year's Eve.
In a statement circulated on social media, the jihadist group said one of the "soldiers of the caliphate" had carried out the attack on the Reina nightclub.
The attack shook NATO member Turkey as it tries to recover from a failed July coup and a series of deadly bombings in cities including Istanbul and the capital Ankara, some blamed on Islamic State and others claimed by Kurdish militants.
Nationals of Saudi Arabia, Morocco, Lebanon, Libya, Israel, a Turkish-Belgian dual citizen and a Franco-Tunisian woman were among those killed, officials said. Saudi newspaper al-Riyadh said five of the dead were from Saudi Arabia.
Turkey faces multiple threats including spillover from the war in Syria. Beside its cross-border campaign against Islamic State, it is fighting Kurdish militants in its southeast.
The New Year's Day attack came five months after a failed military coup, in which more than 240 people were killed, many of them in Istanbul, as rogue soldiers commandeered tanks and fighter jets in a bid to seize power.
> At least 35 killed, 40 wounded in Istanbul nightclub 'terror attack'